Systems and methods to nitrogen-infuse and dispense beverages

ABSTRACT

In a method for infusing a gas from a gas source into a liquid beverage, liquid beverage is driven from a beverage container into a liquid inlet port of a venturi mixing device. Nitrogen is infused into the liquid beverage by driving nitrogen through a gas inlet port of the venturi mixing device, thereby delivering nitrogen-infused liquid beverage to a discharge port of the venturi mixing device. The nitrogen-infused liquid beverage is poured from the discharge port through a faucet.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit and is a Continuation-in-Partapplication of U.S. patent application Ser. No. 15/460,383, filed Mar.16, 2017, which is a non-provisional of U.S. Provisional PatentApplication Ser. No. 62/309,006, filed Mar. 16, 2016, the entirety ofeach of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to systems and methods forliquid beverage dispensing and, more specifically, to systems andmethods for infusing compressed gases such as nitrogen into chilledbeverages such as coffee, and dispensing the gas-infused chilledbeverages in a manner that causes a pleasing head of foam to be createdand maintained on the surface of the beverage during and afterdispensing into a receiving container.

2. Description of the Related Art

The storing and dispensing of chilled beverages using compressednitrogen and other gases is used to generate a pleasing head of foam toform on the surface of beverages when they are dispensed into a cup or amug. Existing nitrogen infusion typically employ porous membranes orother elaborate and bulky mixing components cause such infusion. Manysuch systems require gas permeable membranes that are subject toclogging. Other systems employ elaborate liquid and gas mixing schemes,which include multiple regulated liquid and gas pressures to achieve thedesired gas infusion in combination with an acceptable dispensing rateand a desired appearance.

Thus, there is a need for chilled beverage gas-infusion and dispensingsystems and methods that are simpler, have fewer components and aretherefore easier to maintain, more reliable and have a lower cost thanexisting systems.

There is also a need for gas-infusion and dispensing systems and methodsthat consistently provide a high density, long-lasting head on dispensedchilled coffee.

There is also a need for gas-infusion and dispensing systems and methodthat provide a user-selectable proportion of head-to-settled liquid.

There is also a need for gas-infusion and dispensing systems and methodsthat infuse increased proportions of gas compared to existing systems,thereby providing a proportion of head-to-settled liquid, and a headdensity that is considered most appealing to those consuming thebeverage.

SUMMARY OF THE INVENTION

The disadvantages of the prior art are overcome by the present inventionwhich, in one aspect, is a device for infusing a gas from a gas sourceinto a liquid beverage. A beverage container defines an interior forholding the liquid beverage therein. A venturi mixing device has aliquid inlet port in fluid communication with the beverage container, agas inlet port in fluid communication with the gas source and adischarge port. The venturi mixing device is configured to infuse thegas received from the gas source into liquid beverage received from thebeverage container. A faucet is in fluid communication with thedischarge port of the venturi mixing device and is configured todispense the liquid beverage infused with the gas.

In another aspect, the invention is a coffee serving device thatincludes a nitrogen tank, a pressure regulator, a coffee tank, a flowrestricting device and a venturi mixing device. The pressure regulatoris in fluid communication with the nitrogen tank. The coffee tankdefines an interior for holding liquid coffee therein. An input fittingthat is in fluid communication with the interior of the coffee tankcouples the coffee tank to the pressure regulator. An output fitting isin fluid communication with the interior of the coffee tank. The coffeetank is configured so that gas pressure received through the inputfitting forces coffee out of the beverage container through the outputfitting. A flow restricting device is in fluid communication with thefirst pressure regulator. A venturi mixing device has a liquid inletport in fluid communication with the output fitting, a gas inlet port influid communication with the flow restricting device and a dischargeport. The venturi mixing device is configured to infuse nitrogenreceived through the flow restricting device into the coffee receivedfrom the output fitting of the beverage container. A faucet is in fluidcommunication with the discharge port of the venturi mixing device andis configured to dispense the coffee infused with nitrogen.

In yet another aspect, the invention a method of servingnitrogen-infused liquid beverage, in which liquid beverage is drivenfrom a beverage container into a liquid inlet port of a venturi mixingdevice. Nitrogen is infused into the liquid beverage by driving nitrogenthrough a gas inlet port of the venturi mixing device, therebydelivering nitrogen-infused liquid beverage to a discharge port of theventuri mixing device. The nitrogen-infused liquid beverage is pouredfrom the discharge port through a faucet.

These and other aspects of the invention will become apparent from thefollowing description of the preferred embodiments taken in conjunctionwith the following drawings. As would be obvious to one skilled in theart, many variations and modifications of the invention may be effectedwithout departing from the spirit and scope of the novel concepts of thedisclosure.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS

FIG. 1A is a schematic diagram of a first embodiment of a beveragegas-infusion and dispensing system.

FIG. 1B is a schematic diagram of the embodiment shown in FIG. 1Aemploying both a needle valve and an orifice in series.

FIG. 2 is a schematic diagram of a second embodiment of a beveragegas-infusion and dispensing system.

FIG. 3 is a schematic diagram of a third embodiment of a beveragegas-infusion and dispensing system.

FIG. 4 is a flow chart showing one method of nitrogen-infusing anddispensing a beverage.

FIG. 5 is a flow chart showing a method of gas-infusing and dispensing abeverage.

FIG. 6 is a schematic diagram of a beverage dispensing faucet assembly.

FIG. 7 is a schematic diagram of a first example of a venturi mixingdevice.

FIG. 8 is a schematic diagram of a second example of a venturi mixingdevice.

FIG. 9 is a schematic diagram of a third example of a venturi mixingdevice.

FIG. 10 is a chart that illustrates the percent volume of settled headversus the amount of infused nitrogen for a particular chilled coffeebeverage that is dispensed.

FIG. 11 is a tabulation of data and results from dispensing experimentsconducted with one representative embodiment of the invention.

FIG. 12 is a chart that illustrates equivalent orifice sizes associatedwith the acceptable and desired ranges of FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the invention is now described in detail.Referring to the drawings, like numbers indicate like parts throughoutthe views. Unless otherwise specifically indicated in the disclosurethat follows, the drawings are not necessarily drawn to scale. As usedin the description herein and throughout the claims, the following termstake the meanings explicitly associated herein, unless the contextclearly dictates otherwise: the meaning of “a,” “an,” and “the” includesplural reference, the meaning of “in” includes “in” and “on.”

As shown in FIG. 1A, a gas infusion system 100 includes a pressured gascylinder 104 that contains a gas or a gas mixture, which in oneembodiment includes pure or substantially pure nitrogen. A pressureregulator 109 provides a regulated flow of gas into line 108 at apredetermined pressure. Typically, the regulator 109 would maintain gaspressure within the range of about 15 psi to 80 psi. In one embodiment,the regulator 109 maintains the gas pressure in a range of about 25 psito 35 psi and in one specific embodiment it maintains the gas pressurewithin a range of about 28 psi to 32 psi. Depending on the specificapplication, the gas cylinder 104 may be located near to the beveragefaucet assembly 101. In some applications, the gas cylinder 104 may belocated away from beverage faucet assembly 101 for safety reasons. Anoptional secondary pressure regulator 107 may be provided near beveragefaucet assembly 101 as a convenience, whereby the regulated pressure maybe easily adjusted.

Line 108 or optional regulator 107 (if used), connects to lines 114A and114B. Line 114B connects to an inlet port of pressurized beverage tank102, where the connection may utilize a quick disconnect fitting 105 ofa type that is well known in the beverage industry. Line 114A connectsto the inlet port of a flow restricting device, such as valve 132V. Aflow restricting orifice 132O may be used in place of valve 132V, andother types of gas flow restricting devices may also be used. In oneembodiment, a precision needle valve may be used.

The exit port of valve 132V is connected to line 116 which connects tothe suction inlet 140S of venturi mixing device 140. Line 115 connectsthe exit port of beverage tank 102 to pressure inlet port 140P ofventuri mixing device 140. Line 111 connects exit port 140E of venturimixing device 140 to beverage faucet assembly 101. When faucet 103 isclosed, pressures within system 100 are in equilibrium. Check valves orball valves (not shown) may be used in line 115 to prevent reverse flow(or shut off flow) of beverage from mixing device 140 into line 115toward tank 102, and/or in line 116 to prevent reverse flow (or shut offflow) of gas, liquid beverage, or both through suction port 140S intoline 116.

To dispense a gas-infused beverage, an operator moves faucet handle 118to a partially-open or fully-open position. This allows pressurized gaswithin line 108 and then line 114B to displace liquid beverage from tank102 causing liquid beverage to flow from the exit port of tank 102 intoline 115. Tank 102 may be located within a refrigerator or refrigerationunit as commonly known in the beverage industry. Liquid beverage in line115 then flows into pressure inlet port 140P of venturi mixing device140. Simultaneously, pressurized gas in line 114A flows into and throughvalve 132V, exiting at a reduced pressure into line 116 and then flowinginto suction inlet 140S. Within venturi mixing device 140, liquidbeverage flows through a reduced cross-sectional area flow restrictionadjacent suction inlet 140S as is well known for venturi mixing devices.The flow restriction causes a higher velocity and reduced staticpressure within the beverage flow. The reduced static pressure entrainsgas within line 116 and infuses the gas into the beverage flow. Thegas-infused beverage exits port 140E into line 111. Finally, thegas-infused beverage flows through line 111 and is dispensed from faucet103 into a receiving container.

As shown in FIG. 1B, an orifice 132O and a precision needle valve 132Vmay both be used, where the orifice 132O and valve 132V are arranged inseries.

As shown in FIG. 2, an alternate embodiment of a gas infusion system 200employs a beverage bag 216 to hold the beverage. Beverage bags arecommercially available in various sizes and with different materials ofconstruction. Generally, a container of 1 to 5 gallons is utilized forthe present invention, but any suitable container of size convenient tothe intended application may also be utilized. A pressured gas cylinder204 contains a gas or a gas mixture, preferably pure or substantiallypure nitrogen. Pressure regulator 209 provides a regulated flow of gasinto line 208 at a predetermined pressure. In one embodiment, anacceptable pressure within a range of about 15 psi to 80 psi, in certainapplications the pressure is within a range of about 25 psi to 35 psi,and in certain specific applications the pressure is within a range ofabout 28 psi to 32 psi. Gas cylinder 204 may be located near to, orremotely from beverage faucet assembly 201. Gas cylinder 204 may belocated in a remote location, away from beverage faucet assembly 201 forsafety reasons. Optional secondary pressure regulator 207 may beprovided near beverage faucet assembly 201 as a convenience, whereby theregulated pressure may be easily adjusted. Line 208 or optionalregulator 207 (if used), connects to line 214A. Line 214A connects tothe inlet port of a flow restricting device, illustrated as valve 232V.A flow restricting orifice 232O may be used in place of valve 232V, andother types of gas flow restricting devices may also be used. The exitport of valve 232V is connected to line 216 which connects to thesuction inlet 240S of venturi mixing device 240. Line 215 connects theexit port of flexible beverage bag 216 to the inlet port of pump 210.Beverage bag 216 may be contained in a box (not shown). The box may becorrugated cardboard while the bag 216 may be constructed of anymaterial accepted for use in the food and beverage industry. Pump 210may be an air driven diaphragm pump as commonly known in the beverageindustry, optionally driven using compressed gas from gas cylinder 204.Pump 210 may also be another type of pump such as an electrically-drivenpump configured to operate when faucet handle 218 is partially or fullyopened. The exit port of pump 210 connects to pressure inlet port 240Pof venturi mixing device 240. Line 211 connects exit port 240E ofventuri mixing device 240 to beverage faucet assembly 201. When faucet203 is closed, pressures within system 200 are in equilibrium. Checkvalves (not shown) may be used to in line 215 to prevent reverse flow ofbeverage from mixing device 240 into line 115 toward pump 210, and/or inline 216 to prevent reverse flow of gas, liquid beverage, or boththrough suction port 240S into line 216. To dispense a gas-infusedbeverage, an operator moves faucet handle 218 to a partially-open orfully-open position. This causes pump 210 to operate and displace liquidbeverage from bag 216 into line 215, through pump 210, flowing thoughthe pump exit port and then into pressure inlet port 240P of venturimixing device 240. Simultaneously, pressurized gas in line 208 and thenline 214A flows into and through valve 232V, exiting at a reducedpressure into line 216 and then flowing into suction inlet 240S. Withinventuri mixing device 240, liquid beverage flows through a reducedcross-sectional area flow restriction adjacent suction inlet 240S as iswell known for venturi mixing devices. The flow restriction causes ahigher velocity and reduced static pressure within the beverage flow.The reduced static pressure entrains gas within line 216 and infuses thegas into the beverage flow. The gas-infused beverage exits port 240Einto line 211. Finally, the gas-infused beverage flows through line 211and is dispensed from faucet 203 into a receiving container. Bag 216 maybe located within a refrigerator or refrigeration unit as commonly knownin the beverage industry.

Another embodiment of a beverage dispensing system 300 is shown in FIG.3. A pressured gas cylinder 304 contains a gas or a gas mixture, whichcan be pure or substantially pure nitrogen. Pressure regulator 309provides a regulated flow of gas into line 308 at a predeterminedpressure. An acceptable pressure includes a pressure within the range ofabout 15 psi to 80 psi, in certain applications the pressure is within arange of about 25 psi to 35 psi, and in certain specific applicationsthe pressure is within a range of about 28 psi to 32 psi. Gas cylinder304 may be located near to, or remotely from beverage faucet assembly301. Gas cylinder 304 may be located in a remote location, away frombeverage faucet assembly 301 for safety reasons. Optional secondarypressure regulator 307 may be provided near beverage faucet assembly 301as a convenience, whereby the regulated pressure may be easily adjusted.Line 308 or optional regulator 307 (if used), connects to lines 314A and314B. A flexible beverage bag 350 is contained by a semi-rigid container352 such as a cardboard box, comprising a structurally-constrainedbag-in-box arrangement. One example of such a bag-in-box arrangement isdisclosed in U.S. Pat. No. 4,796,788 to Bond, which is incorporatedherein by reference. Container 352 is sized to fit within a structurallyrigid container 352 with a lid 356 suitably attached using a hinge orother fastening arrangement. Beverage bag 350 can include two layers,with an inner layer to contain a liquid beverage, a separate outer layersurrounding the inner layer, a beverage outlet port 355 that connects tothe volume formed by the bag inner layer, and a pressure inlet port 354that connects to the volume formed between the bag layers. The outerlayer of the bag is confined by container 352, and introduction of thepressurized gas through port 353 from line 314B causes the bag innerlayer to be compressed thereby causing an outlet flow of beverage frombeverage outlet port 355. Line 314A connects to the inlet port of a flowrestricting device, illustrated as valve 332V. A flow restrictingorifice 332O may be used in place of valve 332V in certain applications,and other types of gas flow restricting devices well known to the artmay also be used. The exit port of valve 332V is connected to line 316which connects to the suction inlet 340S of venturi mixing device 340.Line 315 connects the exit port 355 of beverage bag 350 to pressureinlet port 340P of venturi mixing device 140. Line 311 connects exitport 340E of venturi mixing device 340 to beverage faucet assembly 301.When faucet 303 is closed, pressures within system 300 are inequilibrium. Check valves (not shown) may be used in line 315 to preventreverse flow of beverage from mixing device 340 into line 315 toward bag350, and/or in line 316 to prevent reverse flow of gas, liquid beverage,or both through suction port 340S into line 316. To dispense agas-infused beverage, an operator moves faucet handle 318 to apartially-open or fully-open position. This allows pressurized gaswithin line 308 and then line 314B to displace liquid beverage from bag350 causing liquid beverage to flow from bag exit port 355 into line315. Liquid beverage in line 315 then flows into pressure inlet port340P of venturi mixing device 340. Simultaneously, pressurized gas inline 314A flows into and through valve 332V, exiting at a reducedpressure into line 316 and then flowing into suction inlet 340S. Withinventuri mixing device 340, liquid beverage flows through a reducedcross-sectional area flow restriction adjacent suction inlet 340S as iswell known for venturi mixing devices. The flow restriction causes ahigher velocity and reduced static pressure within the beverage flow.The reduced static pressure entrains gas within line 316 and infuses thegas into the beverage flow. The gas-infused beverage exits port 340Einto line 311. Finally, the gas-infused beverage flows through line 311and is dispensed from faucet 303 into a receiving container. Container352 may be located within a refrigerator or refrigeration unit ascommonly known in the beverage industry.

FIG. 4 illustrates a method 400 to nitrogen-infuse and dispense abeverage which could be employed using the embodiments shown in FIGS. 1and 3. Step 402 includes providing a regulated pressurized source ofpure or substantially pure nitrogen; a beverage storage vessel; aventuri mixing device with a pressure inlet port, a suction inlet portand exit port; a throttling device; and a beverage faucet. Step 404includes utilizing the regulated source of nitrogen to induce apressurized flow of liquid beverage from a storage vessel into thepressure inlet of the venturi mixing device. Step 406 includes utilizingthe same regulated source of nitrogen to cause a flow of nitrogenthrough the throttling device to cause a reduced-pressure nitrogen flow.Step 408 includes supplying the reduced-pressure nitrogen flow to thesuction inlet of the venturi mixing device. Step 410 includes mixing theliquid beverage and reduced-pressure nitrogen flow within the venturimixing device to obtain a nitrogen infused liquid beverage. Step 412includes supplying the nitrogen-infused liquid beverage to a beveragefaucet and dispensing into a receiving container.

In one embodiment of a gas infusion method 500, as shown in FIG. 5, step502 includes providing a regulated pressurized source of pure orsubstantially pure gas; a pump; a beverage storage vessel; a venturimixing device with a pressure inlet port, a suction inlet port and exitport; a throttling device; and a beverage faucet. Step 504 includesutilizing the pump to induce a pressurized flow of liquid beverage fromthe storage vessel into the pressure inlet of the venturi mixing device.Step 506 includes utilizing the regulated source of gas to cause a flowof gas through the throttling device to cause a reduced-pressure gasflow. Step 508 includes supplying the reduced-pressure gas flow to thesuction inlet of the venturi mixing device. Step 510 includes mixing theliquid beverage and reduced-pressure gas flow within the venturi mixingdevice to obtain a nitrogen infused liquid beverage. Step 512 includessupplying the gas-infused liquid beverage to a beverage faucet anddispensing into a receiving container.

One embodiment of a dispensing faucet assembly is shown in FIG. 6, inwhich a beverage faucet 601 can include a slow pour faucet 603 equippedwith tap handle 618. Faucet 603 can also be equipped with a restrictornozzle 617 which can further include a restrictor disc (not shown) ascommonly known in the beverage industry for dispensing stout beers.Beverage faucet 601 may help provide a high density, long-lastingsettled head on chilled coffee dispensed according to embodiments of thepresent invention, in particular when operated using predeterminedpressures and temperatures. Beverage faucet 601 may also comprisemultiple slow pour faucets for dispensing multiple beverages from asingle location.

A first example of a venturi mixing device 740, as shown in FIG. 7,includes pressure inlet port 740P, suction inlet port 740S, flowrestriction 740T and exit port 740E. Pressurized liquid beverage entersthrough pressure inlet port 740P and pressurized gas enters throughsuction inlet port 740S. Within venturi mixing device 740, liquidbeverage flows through flow restriction 740T with a reducedcross-sectional area as is well known for venturi mixing devices. Flowrestriction 740T causes a higher velocity and reduced static pressurewithin the beverage flow adjacent port 740S which entrains gas enteringthrough port 740S and infuses the gas into the beverage flow. Thegas-infused beverage exits device 740 through exit port 740E. U.S. Pat.No. 2,210,846 to Aghnides, U.S. Pat. No. 2,571,870 to Hayes, and U.S.Pat. No. 2,800,313 to Targosh et al. illustrate venturi mixing devicesor eductors and are incorporated herein by reference for the purpose ofshowing venturi/eductor devices and methods of making such devices.

A second example of a venturi mixing device 840, as shown in FIG. 8,includes pressure inlet port 840P, suction inlet port 840S, flowrestriction 840T and exit port 840E. Pressurized liquid beverage entersthrough pressure inlet port 840P and pressurized gas enters throughsuction inlet port 840S. A nozzle 840N may be present and protrude intoflow restriction 840T. Within venturi mixing device 840, liquid beverageflows through flow restriction 840T with a reduced cross-sectional areaas is well known for venturi mixing devices. Flow restriction 840Tcauses a higher velocity and reduced static pressure within the beverageflow adjacent port 840S which entrains gas entering through port 840Sand infuses the gas into the beverage flow. Nozzle 840N may enhance thegas infusion into the liquid beverage. The gas-infused beverage exitsdevice 840 through exit port 840E.

A third example of a venturi mixing device 940, as shown in FIG. 9,includes an eductor that includes pressure inlet port 940P, suctioninlet port 940S, flow nozzle 940T and exit port 940E. Pressurized liquidbeverage enters through pressure inlet port 940P and pressurized gasenters through suction inlet port 940S. Within venturi mixing device940, liquid beverage flows through flow nozzle 940T with a reducedcross-sectional area as is well known for eductors. Flow nozzle 940Tcauses a higher velocity and reduced static pressure within the beverageflow adjacent port 940S which entrains gas entering through port 940Sand infuses the gas into the beverage flow. The gas-infused beverageexits device 940 through exit port 940E. In one embodiment, the eductorcould include a T-fitting.

A venturi mixing device may be fabricated as a single unit asillustrated in FIGS. 7 through 9, or may be assembled using commonlyavailable pipe or tube fittings. For example, a venturi mixing assemblymay be constructed of a standard tee fitting and two reduction fittings,wherein the small ends of the reduction fittings are sized to match theends of the tee fittings. The small ends of the first and secondreduction fittings are assembled to either end of the tee fitting. Whenused in the present invention, the liquid beverage flows into the largeend and then the small end of the first reduction fitting, through thetee fitting and past the right-angle port of the tee, through the smallend of the second reduction fitting and then exits through the large endof the second reduction fitting. The reduced cross-sectional area withinthe tee fitting creates higher velocity and reduced static pressurewithin the beverage flow adjacent the right-angle port of the teefitting, and thus the right angle port of the tee functions as thesuction inlet of the venturi mixing assembly. In this manner a venturimixing assembly may be assembled from inexpensive pipe or tube fittingswhich may be lower cost as compared to single unit venturi mixingdevices.

Embodiments of the present invention include components that cancooperate to gas-infuse, dispense and provide a pleasing proportion ofsettled head on a liquid beverage. The volume of the settled headproduced by embodiments of the present invention can be greater thanabout fifteen percent, greater than about twenty five percent, and canalso be about thirty percent of the total volume occupied by the settledhead and the underlying liquid beverage within a receiving container.The liquid beverage may be dispensed using a pressure within the rangeof about 15 psi to 80 psi, and in one embodiment within a range of about25 psi to 45 psi, and in a specific embodiment within a range of about28 psi to 32 psi. In some embodiments, the liquid beverage is cooled toa temperature of about 33° F. to 40° F. prior to dispensing. In otherembodiments, the liquid beverage is coffee that is cooled to atemperature of about 34° F. to 37° F. prior to dispensing. The volume ofthe settled head may be adjusted by a user and can depend upon thepressure and temperature of the chilled beverage as well as the designof the individual components that comprise various embodiments of thepresent invention.

The percent volume of settled head versus the amount of infused nitrogenfor a particular chilled coffee beverage that is dispensed according toembodiments of the invention is shown in FIG. 10. The solid diamondsymbols represent performance for predetermined pressures andtemperatures, the solid circle symbols represent performance for otherpressures and temperatures that fall within the scope of the presentinvention. (The solid triangle symbols represent performance forparticular experiments conducted at about 35 psi regulated gas pressure,liquid beverage temperature of about 35° F., and liquid beverage flow ofabout 0.28 U.S. gallons per minute.) According to FIG. 10, for thisparticular beverage a settled head of greater than about fifteen percentvolume requires nitrogen infusion greater than about 100 parts permillion (ppm) by weight. A settled head of greater than about twentyfive percent requires nitrogen infusion greater than about 220 ppm. Asettled head of about thirty percent requires nitrogen infusion greaterthan about 250 ppm. Now referring to FIG. 1, flow restricting device132V or 132O can be designed to cooperate with a membrane-free eductor140 (such as a venturi) to infuse nitrogen into a liquid beverage atgreater than about 100 ppm by weight for an embodiment of the invention,greater than about 160 ppm for one example of an embodiment of theinvention, and greater than about 250 ppm for another example of anembodiment of the invention. Other types of beverages may requirediffering amounts of infused nitrogen to provide a desired percentage ofsettled head. One beverage may have a differing amount of totaldissolved solids (TDS) than another beverage, and the TDS may influencethe volume of settled head. Increased TDS in a beverage may result inreduced settled head and vice versa.

A tabulation of data and results from dispensing experiments conductedwith a first embodiment of the invention is shown in FIG. 11. In theseexperiments, gas and liquid flow meters were inserted into lines 114Aand 115 (as shown in FIG. 1), respectively, to measure the infusing gasflow and liquid beverage flow, respectively. For example, in oneexperiment the infusing gas was nitrogen, and the liquid beverage waschilled coffee. The regulated gas pressure was about 35 psi, and thechilled coffee temperature was about 35° F. The measured chilled coffeeflow was about 0.28 U.S. gallons per minute (GPM), and the measurednitrogen flow was about 0.35 standard cubic feet per hour (SCFH).Dividing the nitrogen flow by the chilled coffee flow results in a ratioof about 1.25 SCFH/GPM. The calculated gas flow (and nitrogen infusion)for this experiment on a weight basis is about 200 ppm. Performance forvarious embodiments of the invention at various dispensing conditions isdescribed in FIG. 11.

The flow restricting device 132V or 132O is designed to operate withventuri mixing device 140 using known design rules for fluid flowthrough such devices. Embodiments of the invention can include a flowcontrol orifice 132O with a diameter of less than about 0.05 inches foruse with a venturi mixing device 140 that has a through-flow of about 1U.S. gallons per minute or less at predetermined pressures andtemperatures. Embodiments of the invention can include a precisionneedle valve to provide a user-adjustment for infused nitrogen and thusa means to control and adjust the amount of settled head. Other orificeand venturi mixing device sizes and designs fall within the scope of thepresent invention.

As shown in FIG. 12, equivalent orifice sizes are associated with theacceptable and predetermined ranges of FIG. 11. The shaded area 1200represents the acceptable range; the cross-hatched area 1202 representsthe predetermined range. As discussed above, the flow restricting devicecan include valve 132V or orifice 132O. Valve 132V can include aprecision needle valve. The equivalent orifices sizes in FIG. 12 canrepresent the characteristics of valve 132V when adjusted to provide theflow of an orifice of a desired diameter. Embodiments of the inventioncan include a flow restricting device with flow performance equivalentto orifices ranging in diameter from about 0.005 inches to about 0.015inches. For example, the horizontal line 1204 drawn at 0.009 inches inFIG. 12 can represent an orifice 132O of 0.009 inches diameter or avalve 132V adjusted to provide the same flow as a 0.009 inch diameterorifice. The gas flow thus provided results in gas infusion of about 175ppm to about 250 ppm on a weight basis for liquid beverage flows ofabout 1 to about 0.28 U.S. gallons per minute, respectively.

The pressures and temperatures disclosed herein can create conditionsfavorable for dispensing the beverage through a slow pour faucet aspreviously described. As the nitrogen-infused beverage exits the faucetnozzle, the infused nitrogen undergoes a volume expansion of about2.7-to-1 (at 25 psi regulated pressure) to about 3.4-to-1 (at 35 psiregulated pressure) as the infused nitrogen equilibrates to ambientpressure. At these pressures a settled head with a pleasing creamytexture is formed. Higher pressures may cause expansion that is toolarge and/or too rapid, thereby causing excessive foam and/or faucetsputtering. Lower pressures may cause insufficient head with aless-creamy texture.

The above described embodiments, while including the preferredembodiment and the best mode of the invention known to the inventor atthe time of filing, are given as illustrative examples only. It will bereadily appreciated that many deviations may be made from the specificembodiments disclosed in this specification without departing from thespirit and scope of the invention. Accordingly, the scope of theinvention is to be determined by the claims below rather than beinglimited to the specifically described embodiments above.

What is claimed is:
 1. A method of serving nitrogen-infused liquidbeverage, comprising the steps of: (a) driving liquid beverage from abeverage container into a liquid inlet port of a venturi mixing device;(b) infusing nitrogen into the liquid beverage by driving nitrogenthrough a gas inlet port of the venturi mixing device, therebydelivering nitrogen-infused liquid beverage to a discharge port of theventuri mixing device; and (c) pouring the nitrogen-infused liquidbeverage from the discharge port through a faucet.
 2. The method ofclaim 1, wherein the venturi mixing device comprises a membrane-freeventuri mixing device.
 3. The method of claim 2, wherein the venturimixing device includes at least one of an orifice and a needle valve. 4.The method of claim 1, wherein the step of driving the liquid beveragefrom the beverage container comprises a step selected from a listconsisting of: pressurizing the beverage container so as to force liquidbeverage out of the beverage container and pumping liquid beverage outof the beverage container.
 5. The method of claim 1, wherein thenitrogen is stored in a nitrogen tank and further comprising the step ofregulating pressure of the nitrogen to a predetermined range using apressure regulator.
 6. The method of claim 5, wherein the predeterminedrange is between 15 psi and 80 psi.
 7. The method of claim 1, furthercomprising the step of controlling nitrogen flow into the gas inlet portand beverage flow into the liquid inlet port so that the beverageexiting the outlet port includes nitrogen in a range of 120 ppm to 500ppm by weight.
 8. The method of claim 7, wherein the beverage exitingthe outlet port includes nitrogen in a range of 160 ppm to 260 ppm byweight.
 9. A method of serving nitrogen-infused liquid beverage,comprising the steps of: (a) driving liquid beverage from a beveragecontainer into a liquid inlet port of a membrane-free venturi mixingdevice; (b) infusing nitrogen into the liquid beverage by drivingnitrogen through a gas inlet port of the membrane-free venturi mixingdevice, thereby delivering nitrogen-infused liquid beverage to adischarge port of the venturi mixing device; and (c) pouring thenitrogen-infused liquid beverage from the discharge port through afaucet.
 10. The method of claim 9, wherein the venturi mixing deviceincludes at least one of an orifice and a needle valve.
 11. The methodof claim 9, wherein the step of driving the liquid beverage from thebeverage container comprises a step selected from a list consisting of:pressurizing the beverage container so as to force liquid beverage outof the beverage container and pumping liquid beverage out of thebeverage container.
 12. The method of claim 9, wherein the nitrogen isstored in a nitrogen tank and further comprising the step of regulatingpressure of the nitrogen to a predetermined range using a pressureregulator.
 13. The method of claim 12, wherein the predetermined rangeis between 15 psi and 80 psi.
 14. The method of claim 9, furthercomprising the step of controlling nitrogen flow into the gas inlet portand beverage flow into the liquid inlet port so that the beverageexiting the outlet port includes nitrogen in a range of 120 ppm to 500ppm by weight.
 15. The method of claim 14, wherein the beverage exitingthe outlet port includes nitrogen in a range of 160 ppm to 260 ppm byweight.